For questions which are old and unanswered and with a score less than zero, the Roomba may provide automated deletion.
For questions which are sometimes many years old and unanswered and sometimes with a score much more than zero, I would never suggest deletion, nor would I propose Automatic system-generated bounties on old, highly-upvoted, unanswered questions in small sites (or any sites), but is leaving them open and unanswered potentially forever the only approach?
This question is intended to initiate a discussion about old, unanswered and open questions. It does not advocate closing such questions because they are unanswered.